Wattsonic Wattsonic GEN3 (battery)
The Wattsonic GEN3 is a three-phase hybrid inverter and battery storage system for residential and light-commercial solar installations. This ModbusCloud template connects over Modbus TCP to the inverter's built-in LAN dongle at port 502 and reads battery charge or discharge power and state of charge. It also exposes the minimum on-grid SOC setpoint, letting your portal enforce a discharge floor. Monitoring these three registers gives installers a clear live view of battery behavior without relying on the Wattsonic cloud app.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 3, read and write
- Brand
- Wattsonic
- Last updated
Registers (3)
2 read, 1 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| soc | % | Read | |||
| limitsoc | % | Write |
Loading registers…
Send your device list
If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Monitor battery charge and discharge power in real time to verify the system is cycling as expected.
- Track state of charge over each day to detect capacity fade across seasons.
- Alert on the battery SOC dropping to the configured minimum limit during peak grid-demand periods.
- Report daily charge and discharge cycles to building owners for energy accounting.
- Verify that the minimum SOC setpoint was written correctly after a configuration change.
Installation
Confirm that the Wattsonic GEN3 LAN dongle is connected to your local network and that the inverter has obtained an IP address; note the IP from your router's DHCP table.
Connect the ModbusCloud Gateway to the same LAN segment as the inverter. No RS-485 wiring is needed: the inverter exposes Modbus TCP on port 502 natively.
In the ModbusCloud portal, add a new device, import the Wattsonic GEN3 (battery) template, and set the unit ID to 255 and the TCP port to 502 with the inverter's IP address.
Spot-check register 33000 (SOC) in the live data view; if no value appears, verify the IP address and confirm no firewall is blocking port 502 on the local network.
Things to watch for
All registers return 'illegal data address'. What is wrong?
The Wattsonic GEN3 firmware applies a +1 offset to all documented register addresses. If you are querying addresses directly from third-party documentation, add 1 to each address. The addresses in this ModbusCloud template already account for that offset, so if you see this error the unit ID or IP is likely wrong.
The gateway connects but the SOC reads zero or never updates.
Confirm the unit ID is set to 255, which is the correct slave ID for the Wattsonic GEN3 over TCP. Using ID 247 (common for GEN2) will cause silent read failures or stale zero values. Also ensure the LAN dongle has a stable IP and that no other Modbus master is polling the inverter simultaneously.
TCP connection drops or produces frequent timeouts.
The Wattsonic GEN3 LAN dongle (ESP-based) is less stable under continuous polling than its RS-485 interface. Increase the Modbus timeout to at least 10 seconds in the Gateway settings, and set a poll interval no shorter than 10 seconds to reduce the load on the dongle.
Is it safe to write to the minimum SOC setpoint register?
Use the limitsoc write register with care. Writing a value that equals or exceeds the current battery SOC will immediately stop discharging and force the system to draw from the grid. Do not write values outside the documented 10 to 90 percent range, and always restore the original setpoint after any automated control sequence to avoid leaving the battery permanently restricted.
Want to see how it works?
